As the title says, I need to install ubuntu in dual boot with windows 8.1 on my home PC.

I knew that with UEFI partition table was written in GPT, but I found that the partition table on my hard drive is written in MBR, composed by two partitions:

1)BOOT partition, formatted in NTFS has size 1.5 GB and flag boot
2)OS partition, formatted in NTFS covers the rest of the HD.

In UEFI menu(canc at the beginning) Secure Boot and Fast Boot are disabled. I found on the internet that the partition table is MBR if UEFI is setted in Legacy mode, but I can't find this option.

Furthermore, Ubuntu live doesn't recognize any other OS installed on my HD(I booted ubuntu live on a USB stick using UEFI option in the boot menu and it went fine). How should I proceed? Should I convert all the partition table to GPT(I read on the internet it could be done without any loss of data) and then install Gummiboot or should I just install Ubuntu in the old legacy mode and let grub do the rest?Thanks for your help.

2 Answers
2

Your easiest path at this point is to do a BIOS/CSM/legacy-mode install of Ubuntu. You can probably do this by selecting a boot option for your installation medium that does not include the word "EFI" or "UEFI." The result will be just as if you were using an older BIOS-only computer. The biggest drawback to this will be slightly longer boot times than you'd have if you were to boot both OSes in EFI mode.

If you want to do an EFI-mode install of Ubuntu, you'll pretty much have to either re-install Windows or convert it to boot in EFI mode. (There are ways to have two OSes installed in two different boot modes, but they tend to be pretty awkward to manage.)